Structural composites and other reinforced molded articles are commonly made using manufacturing processes such as resin transfer molding and structural resin injection molding. These molding processes have been made more efficient by using reinforcement fibers that are used to make a reinforcement layer or mat. The preformed fiber reinforced layers or mat “preforms” or filament winding prepregs have the approximate shape and size of the molded article.
As the technical requirements for reinforcement products increases, new methods for dispensing and laying down reinforcement fibers are required. One requirement is that the reinforcement fibers be delivered at faster speeds than used previously. Another requirement is that the reinforcement fibers be laid down in varying degrees of thickness or density to achieve the desired reinforcement result. Another requirement is that the reinforcement fibers be laid down in a predetermined orientation.
When preforms are made with specific amounts and specific orientations of the reinforcement fibers, the preforms provide improved strength to the molded product precisely at the weakest or most stressed locations. Because of this new design requirement, there often is a requirement that the fibers be dispensed in a very controlled manner.
Efforts to control the orientation of the fibers have not been entirely successful, especially at the high speeds necessary for commercially successful operations. When typical fiber dispensers are operated at a faster speed, the fibers cannot be successfully laid down in a pattern that is as controlled as is desired.
It is clear that improvements in dispensing precisely oriented fibers in a controlled manner, enabling a more precise distribution of fibers, would be desirable.